The eastern span of the Oakland-San Francisco Bay Bridge under construction. The bridge was opened to traffic on Labor Day last year.

An investigation by the state Senate Transportation Committee has concluded that the California Department of Transportation “systematically” worked to quiet “serious allegations” aimed at the safety of the new eastern span of the Bay Bridge.

The investigation found that “Caltrans managers marginalized dissenters, fired critics, reassigned outspoken engineers and urged those involved to avoid putting details of problems or issues in writing that would have to be disclosed under the state’s Public Records Act.”

Among those interviewed by the committee were MACTEC engineer and quality inspector James Merrill. It was Merrill’s job to inspect the quality of the bridge deck welds in Shanghai, China where they were fabricated. Merrill found that the welds were “riddled with hundreds of cracks,” the Mercury News reports, and the necessary repairs would have added $100 million to the $6.4 billion bridge’s cost in addition to two years of extra work.

Merrill told the committee that Caltrans managers told him he was “being too rigorous” and when MACTEC’s contract expired, Caltrans hired another company to do the inspections.

Merrill told the committee that the bridge, which was opened to traffic on Labor Day last year, is safe, “but that the decks will require expensive retrofits well before the promised 150-year life span of the bridge.”